This invention relates to a disposable diaper having a skin-contacting topsheet provided with an elastic opening for reliable introduction of excretions and also to a method for making this elastic opening.
Japanese Utility Model Application Disclosure Gazette No. 1974-120439 discloses a diaper-cover having a topsheet formed at its central zone with an opening extending longer in the longitudinal direction than in the transverse direction of the topsheet, wherein the opening is provided along its peripheral edge with a longitudinally stretchable elastic member so as to define a closed loop-shaped elastic line. Japanese Patent Application Disclosure Gazette No. 86-41304 also discloses a disposable diaper having a topsheet formed at its central zone with an opening extending longer in the longitudinal direction than in the transverse direction of the topsheet, wherein the opening is provided along its laterally opposite side edges with elastic members, respectively.
The above-identified Japanese Utility Model Application Disclosure Gazette No. 1974-120439 and Japanese Patent Application Disclosure Gazette No. 1986-41304 disclose neither a method for forming the skin-contacting topsheet with the opening nor a method for attaching the elastic member around the opening. It is supposed that the elastic member is attached in an endless fashion along the whole periphery of the opening closely adjacent the peripheral edge and then said elastic member is covered with the peripheral edge of the opening. However, no specific method for this can be found in the specification. In view of the fact that the '439 application relates to a reusable diaper-cover, the method probably employs the cutting and sewing techniques well known in the art. According to the latter, the central portion of the sheet is cut away to form the opening and both side edges of the opening are provided with the respective elastic members bonded to the rear sides of the respective side edges with use of adhesive. Consequently, the diaper provided by the latter is not only unseemly but also is unacceptably poor in the desired strength along the peripheral edge of the opening because the elastic members are not covered at all though they are provided on the rear side of the sheet. Moreover, such an arrangement will not result in the formation of neatly uniform gathers along the whole peripheral edge of the opening and therefore it can not be expected that the whole peripheral edge of the opening tightly bears against the wearer's skin.
With both the diaper-cover and the diaper disclosed in the above identified Japanese Utility Model Application Disclosure Gazette No. 1974-120439 and Japanese Patent Application Disclosure Gazette No. 1986-41304, the opening is elasticized by the elastic member attached thereto so that the periphery thereof tends to rise up from a separately provided topsheet underlying the skin-contacting topsheet. However, the skin-contacting topsheet is provided only around the periphery of the opening with the elastic member and, consequently, the desired degree of such rising effect can not be expected from this well known arrangement. In other words, no adequate space can be obtained between the skin-contacting topsheet centrally formed with the opening and the separately provided topsheet underlying said skin-contacting topsheet. Accordingly, this space often can not serve as a pocket into which excretions should be reliably introduced and the wearer's skin may be undesirably smeared with excretions. Such inconvenience will occur particularly when the diaper is tightly worn on the wearer's body with the skin-contacting topsheet being pressed against the crotch zone of the wearer.
In view of such a problem, it is a principal object of the invention to provide a novel arrangement of a disposable diaper in which there are provided elastic members extending not only along opposite side edges of the opening but also further beyond longitudinally opposite ends of the opening substantially to the longitudinally opposite ends of the skin-contacting topsheet so that the skin-contacting topsheet centrally formed with the opening may rise up from the separately provided topsheet underlying the skin-contacting topsheet by an extent sufficient to form a desired pocket space.